Nizhevsky I. Grounding devices of city substations modernization and parameters control methods improvement

Object of research: processes of different physical nature in the GD of the substations, which are in conditions of long-term exploitation, including located within the city. Objective: to improve the methods of controlling the parameters and modernization of the earthing device of city substations. Methods of research: mathematical and physical modeling. Research results and novelty: The analysis of the results of the survey of existing substations GD, revealed serious violations that lead to deviation of parameters from the norm and to the need to upgradesubstations GD. It is shown that the upgrade of the GD leads to the restoration of its normalized parameters. The mathematical models of GD of simple two-level structures from horizontal or annular electrodes are developed. As a result of the study of the electric field, it was found that the potential on the surface of the earth above the center of the square earthing may be higher than over the electrode. The mathematical model of a complicated two-level GD of a substation is improved, the method of calculation of its electrical characteristics is developed. The method of equalizing electric potentials on the surface of the earth over the cells of the GD of the substation and outside the contour of the GD of the substation has been improved. The connection of the size of the mesh cell with the depth of its laying is established. The theoretical substantiation of the method is fulfilled and a method of measuring the resistance of the GD in the conditions of dense development of the territory is developed. The method is applicable to any nature of ground heterogeneity, any size and configuration of the GD, and the arbitrary placement of the measuring electrodes without finding the zero point potential. Experimental investigations of electrical characteristics of the two-level GD of a substation by the method of physical modeling in an electrolytic bath. The obtained results showed a good coincidence with the results of calculations. The results of the work were implemented at JSC "Kharkivoblenergo" during the modernization of the GD. Theoretical positions and practical conclusions are used in scientific research work and educational process of the department of transmission of electric energy NTU "KhPI" for the preparation of students by the specialty 05070102 - "Electrical systems and networks".